A spate of videos uploaded to YouTube claim to show victories by Russian-backed separatists during intensified fighting in eastern Ukraine.
They may also provide graphic evidence of war crimes.
One recent video shows seven Ukrainian soldiers lined up against a wall after falling to separatists in the eastern city of Krasnyy Partizan. Lying next to the seven captives are two men who appear to lie mortally wounded and another two who are dead.
Later in the video, another dead soldier is shown lying a few meters away.
The footage is being viewed by some as circumstantial evidence that the four fallen soldiers were executed in front of the wall after surrendering.
A summary of the allegations made on the Ukraine@war blog points to single bullet holes in the wall, precisely where the heads of the fallen captives would have been; fresh blood on the ground; and a bullet wound through the face of one of the dead.
Interpreter Magazine casts doubt on the claims, pointing out that there have been ongoing battles and that the holes in the building are not necessarily fresh. Also, only one of the men shown appears to have a head wound (something one might expect in the case of a summary execution).
Medical aid is not given to the wounded soldiers, who, although barely able to speak, are interrogated by the cameraman. In a second video, at least one of the wounded has died.
The captives are not threatened with execution but scolded for coming to eastern Ukraine to "kill our children."
In a third video (WARNING! Graphic Content), the dead captives are piled up along the side of the road as a correspondent for Russian state TV interviews a commander of the pro-Russian Vostok battalion who goes by the nom de guerre Dushman.
He tells the reporter that, although his men offered the Ukrainians the chance to surrender, they refused.
(The reporter -- who sees Western media on the scene and asks Dushman whether they are covering events "fairly" -- labels them as members of the ultranationalist Right Sector group, without providing evidence.)
On January 23, Aleksandr Zakharchenko, prime minister of the self-proclaimed Donetsk People's Republic, announced that his men would no longer be taking prisoners. The statement has been taken by some as an implied threat.
In a separate incident, a video shows (WARNING! Graphic Content) well-known separatist commander Givi physically abusing and tormenting captives who were apparently taken during the recent siege at the Donetsk airport.
Givi, who at one point brandishes a sword, throws the captives from a truck and onto the ground. Taking apparent pleasure in asking if they recognize him (they do), he uses a knife to cut the felt chevrons off their jackets and stuffs them into their mouths.
Living captives are blindfolded and forced back onto a truck before being driven to downtown Donetsk, where several women are seen beating and throwing eggs at them.
Reporters for Russian TV are visible throughout the video.
Oleksandra Matviychuk, head of the Kyiv-based Center for Civil Liberties, calls what appears in the videos "flagrant violations of the Geneva Conventions" and says she is preparing the groundwork for prosecution.
"We are downloading, describing, and archiving every video. And, in parallel, we are actively working to convince our members to ratify the Rome Statute and become a member of the International Criminal Court," she told RFE/RL's Ukrainian Service on January 27.
Social psychologist Viktor Pushkar described the videos as an "attempt to scare Ukrainian soldiers and sow panic in Ukrainians."
However, he said, "in this case, I think the videos will have the opposite effect: If you do this to ours, we're going to have to answer with equal measure."